﻿#region License
// Copyright 2007-2008 Rory Plaire (codekaizen@gmail.com)
/*
 * This license governs use of the accompanying software. If you use the software, you
 * accept this license. If you do not accept the license, do not use the software.
 * 
 * 1. Definitions
 * The terms "reproduce," "reproduction," "derivative works," and "distribution" have the
 * same meaning here as under U.S. copyright law.
 * A "contribution" is the original software, or any additions or changes to the software.
 * A "contributor" is any person that distributes its contribution under this license.
 * "Licensed patents" are a contributor's patent claims that read directly on its contribution.
 * 
 * 2. Grant of Rights
 * (A) Copyright Grant- Subject to the terms of this license, including the license conditions 
 *     and limitations in section 3, each contributor grants you a non-exclusive, worldwide, 
 *     royalty-free copyright license to reproduce its contribution, prepare derivative works 
 *     of its contribution, and distribute its contribution or any derivative works that you create.
 * (B) Patent Grant- Subject to the terms of this license, including the license conditions and 
 *     limitations in section 3, each contributor grants you a non-exclusive, worldwide, royalty-free 
 *     license under its licensed patents to make, have made, use, sell, offer for sale, import, 
 *     and/or otherwise dispose of its contribution in the software or derivative works of the 
 *     contribution in the software.
 * 
 * 3. Conditions and Limitations
 * (A) No Trademark License- This license does not grant you rights to use any contributors' 
 *     name, logo, or trademarks.
 * (B) If you bring a patent claim against any contributor over patents that you claim are 
 *     infringed by the software, your patent license from such contributor to the software 
 *     ends automatically.
 * (C) If you distribute any portion of the software, you must retain all copyright, patent, 
 *     trademark, and attribution notices that are present in the software.
 * (D) If you distribute any portion of the software in source code form, you may do so only under 
 *     this license by including a complete copy of this license with your distribution. If you 
 *     distribute any portion of the software in compiled or object code form, you may only do so 
 *     under a license that complies with this license.
 * (E) The software is licensed "as-is." You bear the risk of using it. The contributors give no 
 *     express warranties, guarantees or conditions. You may have additional consumer rights under 
 *     your local laws which this license cannot change. To the extent permitted under your local laws, 
 *     the contributors exclude the implied warranties of merchantability, fitness for a particular 
 *     purpose and non-infringement.
 * 
 */
#endregion

using System;
using Xunit;

namespace NPack.Tests
{
    public class MersenneTwisterTests
    {
        [Fact]
        public void CreatingMersenneTwisterWithDefaultSeedSucceeds()
        {
            MersenneTwister random = new MersenneTwister();
            Assert.NotNull(random);
        }

        [Fact]
        public void CreatingMersenneTwisterWithSpecificSeedSucceeds()
        {
            MersenneTwister random = new MersenneTwister(Environment.TickCount);
            Assert.NotNull(random);
        }

        [Fact]
        public void CreatingMersenneTwisterWithSpecificKeySucceeds()
        {
            Int32[] key = new Int32[512];
            Random random = new Random();

            for (Int32 i = 0; i < key.Length; i++)
            {
                key[i] = random.Next();
            }

            random = new MersenneTwister(key);

            Assert.NotNull(random);
        }

        [Fact]
        public void CreatingMersenneTwisterWithNullKeyFails()
        {
            Int32[] key = null;
            Assert.Throws<ArgumentNullException>(delegate() { new MersenneTwister(key); });
        }

        [Fact]
        public void GenerateInt32Succeeds()
        {
            MersenneTwister random = new MersenneTwister();
            Int32 value = random.Next();
        }

        [Fact]
        public void GenerateInt32LessThanMaxSucceeds()
        {
            MersenneTwister random = new MersenneTwister();
            Int32 value = random.Next(100);
        }

        [Fact]
        public void GenerateInt32BetweenValuesSucceeds()
        {
            MersenneTwister random = new MersenneTwister();
            Int32 value = random.Next(100, 200);
        }

        [Fact]
        public void GenerateUInt32Succeeds()
        {
            MersenneTwister random = new MersenneTwister();
            UInt32 value = random.NextUInt32();
        }

        [Fact]
        public void GenerateDoubleSucceeds()
        {
            MersenneTwister random = new MersenneTwister();
            Double value = random.NextDouble();
        }

        [Fact]
        public void GenerateBytesSucceeds()
        {
            MersenneTwister random = new MersenneTwister();
            Byte[] buffer = new Byte[256];
            random.NextBytes(buffer);

            Boolean nonZeroExists = false;

            foreach (Byte b in buffer)
            {
                nonZeroExists = (b != 0);

                if (nonZeroExists)
                {
                    break;
                }
            }

            Assert.True(nonZeroExists);
        }

        [Fact]
        public void GenerateBytesWithNullBufferFails()
        {
            MersenneTwister random = new MersenneTwister();
            Byte[] buffer = null;
            Assert.Throws<ArgumentNullException>(delegate() { random.NextBytes(buffer); });
        }
    }
}
